Genus Choristoneura Research Articles

The Spruce Budworm Genome: Reconstructing the Evolutionary History of Antifreeze Proteins.

Insects have developed various adaptations to survive harsh winter conditions. Among freeze-intolerant species, some produce “antifreeze proteins” (AFPs) that bind to nascent ice crystals and inhibit further ice growth. Such is the case of the spruce budworm, Choristoneura fumiferana (Lepidoptera: Tortricidae), a destructive North American conifer pest that can withstand temperatures below −30°C. Despite the potential importance of AFPs in the adaptive diversification of Choristoneura, genomic tools to explore their origins have until now been limited. Here, we present a chromosome-scale genome assembly for C. fumiferana, which we used to conduct comparative genomic analyses aimed at reconstructing the evolutionary history of tortricid AFPs. The budworm genome features 16 genes homologous to previously reported C. fumiferana AFPs (CfAFPs), 15 of which map to a single region on chromosome 18. Fourteen of these were also detected in five congeneric species, indicating Choristoneura AFP diversification occurred before the speciation event that led to C. fumiferana. Although budworm AFPs were previously considered unique to the genus Choristoneura, a search for homologs targeting recently sequenced tortricid genomes identified seven CfAFP-like genes in the distantly related Notocelia uddmanniana. High structural similarity between Notocelia and Choristoneura AFPs suggests a common origin, despite the absence of homologs in three related tortricids. Interestingly, one Notocelia AFP formed the C-terminus of a “zonadhesin-like” protein, possibly representing the ancestral condition from which tortricid AFPs evolved. Future work should clarify the evolutionary path of AFPs between Notocelia and Choristoneura and assess the role of the “zonadhesin-like” protein as precursor of tortricid AFPs.

Convergent herbivory on conifers by Choristoneura moths after boreal forest formation

Mitogenomes are useful markers for phylogenetic studies across a range of taxonomic levels. Here, we focus on mitogenome variation across the tortricid moth genus Choristoneura and particularly the spruce budworm (Choristoneura fumiferana) species complex, a notorious pest group of North American conifer forests. Phylogenetic relationships of Tortricidae, representing two subfamilies, four tribes and nine genera, were analyzed using 21 mitogenomes. These included six newly-sequenced mitogenomes for species in the spruce budworm complex plus three additional Choristoneura species and 12 previously published mitogenomes from other tortricids and one from the Cossidae. We evaluated the phylogenetic informativeness of the mitogenomes and reconstructed a time-calibrated tree with fossil and secondary calibrations. We found that tortricid mitogenomes had conserved protein and ribosomal regions, and analysis of all protein-coding plus ribosomal genes together provided an efficient marker at any taxonomic rank. The time-calibrated phylogeny showed evolutionary convergence of conifer feeding within Choristoneura, with two independent lineages, the Nearctic spruce budworm complex and the Palearctic species Choristoneura murinana, both shifting onto conifers about 11 million years ago from angiosperms. These two host-plant shifts both occurred after the formation of boreal forest in the late Miocene. Haplotype diversification within the spruce budworm complex occurred in the last 4 million years, and is probably linked to the initial cooling cycles of the Northern Hemisphere in the Pliocene.

A review of the tachinid parasitoids (Diptera: Tachinidae) of Nearctic Choristoneura species (Lepidoptera: Tortricidae), with keys to adults and puparia

The genus Choristoneura (Lepidoptera: Tortricidae) comprises about 16 species in the Nearctic Region and includes several destructive pests of importance to forestry and agriculture. The following 15 species of Tachinidae (Diptera) are recognized as occasional or common parasitoids of Choristoneura species in this region: Actia diffidens Curran, Actia interrupta Curran, Ceromasia auricaudata Townsend, Compsilura concinnata (Meigen), Cyzenis incrassata (Smith), Eumea caesar (Aldrich), Hemisturmia parva (Bigot), Hyphantrophaga blanda (Osten Sacken), Hyphantrophaga virilis (Aldrich and Webber), Lypha fumipennis Brooks, Madremyia saundersii (Williston), Nemorilla pyste (Walker), Nilea erecta (Coquillett), Phryxe pecosensis (Townsend), and Smidtia fumiferanae (Tothill). Keys to the adults and puparia of these tachinid species are provided. The known distribution, biology, and rates of parasitism are reviewed for each species and published host records from Choristoneura species are listed. Colour habitus images of adults, illustrations of all puparia, and illustrations of features mentioned in the adult key are included. Thirteen other species of Tachinidae recorded from Choristoneura species but excluded from the main text as highly dubious, rare, or accidental records are briefly discussed.

Evidence for directional selection acting on pheromone-binding proteins in the genus Choristoneura.

Patterns of nucleotide variation consistent with the action of natural selection have been discovered at a number of different gene loci. Here, pheromone-binding proteins (PBPs) are examined to determine if selection has acted to fix amino acid changes in PBPs in lineages in which pheromone changes have occurred. PBPs from five different species of moths in the genus Choristoneura were sequenced, along with the PBP of Argyrotaenia velutinana, which serves as an outgroup. Three independent major pheromone changes are represented within this group of five Choristoneura species. Two different lineages show evidence for selection based on polymorphism and divergence comparisons and comparisons of rates of replacement evolution to silent and noncoding evolution. Along one of these lineages, leading to Choristoneura fumiferana, there has been a change to an aldehyde pheromone from an acetate pheromone. The second branch does not appear to be associated with a major pheromone change. Other branches in the tree show a trend toward greater replacement fixation than expected under neutrality. This trend could reflect undetected selective events within this group of PBPs. Selection appears to have acted to fix amino acid changes in the PBP of moths from the genus Choristoneura, but it is not clear that this selection is due to pheromone changes between species.

MORPHOLOGICAL STUDY OF MALE GENITALIA WITH PHYLOGENETIC INFERENCE OF CHORISTONEURA LEDERER (LEPIDOPTERA: TORTRICIDAE)

AbstractMale genitalia of Choristoneura species from the Nearctic Region and Palaearctic Region are described and illustrated. The study revealed that the male genitalia are among the most important body parts that contain valuable morphological characters for species distinction or grouping in this genus. They are potentially useful in the clarification of the taxonomic status of species in closely related species groups, such as the spruce budworm species complex in North America.On the basis of 17 interpretable male genital characters and their corresponding evolutionary states, the phylogeny of the genus Choristoneura is inferred and proposed. Nine species groups are recognized: (1) fumiferana, pinus, biennis, orae, occidentalis, lambertiana, carnana, retiniana, and spaldingiana; (2) diversana, murinana, metasequoiacola, and jezoensis; (3) longicellana; (4) lafauryana; (5) conflictana and fractivittana; (6) hebenstreitella, adumbratana, and luticostana; (7) albaniana and lapponana; (8) rosaceana and parallela; and (9) obsoletana and zapulata.Morphological evidence obtained in the present study suggests that two conifer-feeding species groups of Choristoneura, species group 1 from the Nearctic Region and species group 2 from the Palaearctic Region, are related. They represent the least evolved species groups in the genus. Choristoneura rosaceana, C. parallela, C. obsoletana, and C. zapulata, representing some of the species feeding on deciduous trees, are among the most evolved Choristoneura species.

A comparison of three granulosis viruses isolated from Choristoneura spp

Three granulosis viruses from the genus Choristoneura were characterized by restriction endonucleases, thermal denaturation of their DNAs, polyacrylamide gel electrophoresis of the viral proteins, and peptide mapping of the granulins. It was shown that although these viruses are very closely related genetically, they have minor but distinct differences in their restriction patterns. Differences were also observed in their polypeptides when examined on polyacrylamide gels. The sizes of the genomes were on the order of 107,000 base pairs. The size of the granulins was identical.

Characterization of DNA from three nuclear polyhedrosis viruses pathogenic for Choristoneura sp

Three nuclear polyhedrosis viruses isolated from larvae of the insect genus Choristoneura showed polyhedrins of 28–30,000 daltons, genome sizes of 78–82 × 10 6 daltons, and guanine plus cytosine contents of 47.9–49.4%. It was demonstrated by comparison of restriction endonuclease fragment patterns that two of the viruses are closely related genetically.

Release and Recovery of Phosphorus-32 Tagged Jack Pine Budworm Larvae in the Field (Lepidoptera: Tortricidae)

Late-stage larvae of the genus Choristoneura drop readily from their host trees when disturbed. This phenomenon has been discussed for the spruce budworm by Craighead (1924), Wellington and Henson (1947), and Morris and Mott (1963). Some larvae are able to return to the tree crowns, but many are lost to predators or are unable to reestablish on suitable host plants. Larvae of the jack pine budworm, C. pinus pinus Freeman, exhibit similar behavior (Jennings 1971). If a large proportion of the larvae can be stimulated to drop from the host trees, and if few are able to return, the dropping behavior may be used advantageously to reduce populations. This note reports information on return of larvae from the ground to overstory jack pines.

ON CONIFEROPHAGOUS SPECIES OF CHORISTONEURA (LEPIDOPTERA: TORTRICIDAE) IN NORTH AMERICA: III. SOME CHARACTERS OF IMMATURE FORMS HELPFUL IN THE IDENTIFICATION OF SPECIES

AbstractPigmentation of heads and prothoracic shields of last-instar larvae, colour of pupae, and frequencies of haemolymph colour morphs in fresh pupae are used to support the taxonomic differentiation of the following members of the genus Choristoneura: fumiferana, biennis, orae, occidentalis, viridis, subretiniana, pinus pinus, p. maritima, and lambertiana. These characters are statistical in nature and not competent to relate a single individual unequivocally to a taxonomic group; nevertheless, a key is developed to assist identification of populations on the basis of the characters described. Interspecific relationships within the genus are considered.

SOME ASPECTS OF THE EPIDEMIOLOGY OF A MIGROSPORIDIAN PARASITE OF THE SPRUCE BUDWORM, CHORISTONEURA FUMIFERANA (CLEM.)

Limited tests indicate that the microsporidian parasite Perezia fumiferanae is restricted to insect hosts of the genus Choristoneura and for practical purposes to the single species Choristoneura fumiferana (Clem.). Frozen spores of this parasite were found to be infectious longer than those kept under other conditions but no spores were infectious after 6 months' storage. There are two distinct methods of infection, oral and congenital. Immature eggs within infected female insects are infected by schizonts which develop into spores after the eggs are laid. All infected females, regardless of the degree of infection, transmit the parasite to their offspring, and for practical purposes all the progeny of such females are infected. Offspring of heavily infected females appear to contain more spores than those of lightly infected females. Infected males are sometimes capable of transmitting the parasite to a portion of their offspring. Congenital transmission is responsible for the passage of the parasite from host generation to generation. Increase in the incidence of the parasite occurs by oral ingestion of spores but the habits of the host larvae restrict most transmission to the late larval instars.

THE EXTERNAL ANATOMY OF THE SPRUCE BUDWORM CHORISTONEURA FUMIFERANA (CLEM.) (LEPIDOPTERA, TORTRICIDAE)

For reasons which will be given in a forthcoming taxonomic paper, the spruce budworm, Archips fumiferana (Clem.), is here transferred to the genus Choristoneura Lederer, 1859, Wien Ent. Monatschr., 3:242. Genotype: Tortrix rusticana Treitschke, designated by Fernald, 1908, The genera of the Tortricidae and their types, p. 53. The transfer is made at present in order that this species may be properly referred to in a following paper dealing with its external anatomy.